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SCU research sheds light on how plant species invade

Wednesday, Nov. 28, 2012

It’s always been a bit of a puzzle—why do some species that get introduced outside their native areas become terrible invasive pests, while others either die out or poke along without bothering anyone? Recent research by ESS professor Virginia Matzek has helped shed more light on this question.

One longstanding theory about plant invaders is that they have greater plasticity than non-invaders. Plasticity is the ability to react to local conditions with different appearances or behaviors—for instance, the way a houseplant deprived of light will stretch out longer stems and make fewer leaves than well-lit plants. If invasive species are more inherently flexible in how they react to climate, for instance, they may be able to invade a wider area than less plastic species.

Matzek grew ten species of pines in the greenhouse—five that were known to be invasive on at least two continents, and five that had been widely introduced around the world but had never shown invasive characteristics. By altering nitrogen availability to the two groups, she could see how plant traits like photosynthetic capacity and water-use efficiency reacted to high or low levels of resource availability.

Matzek found that invaders were not more plastic for any of the 17 traits she measured. Instead, invaders seemed to succeed by simply being better than non-invaders at a number of essential plant functions, including producing more leaves and more efficiently using nutrients for photosynthesis.

Many studies have compared plasticity in invader and non-invader groups, but this study was a step forward because all the species were closely related, so differences between the invasive and non-invasive species are likely to be essential to their invasiveness. The paper, “Trait values, not trait plasticity, best explain invasive species’ performance in a changing environment,” was published in PLOS One and can be read here.